The invention relates to a static mixing element for a flange transition in a pipeline and to a pipeline having a mixing element of this kind.
Static mixers are known which are arranged in a pipe section of a pipeline. For the installation of a pipe section of this kind into the pipeline two flange pairs must as a rule be present: two flanges at the pipe section and two associated flanges at the pipeline. Static mixers of this kind cause small pressure losses if they do not greatly narrow the cross-section of the pipe sectionxe2x80x94which is as a rule the casexe2x80x94and thus cause only to a small extent a shedding of vortices which has a high dissipation of the flow energy as a result.
A flange mixer, for the installation of which only one flange pair is required, is known from U.S. Pat. No. 5,839,828. This flange mixer is formed in a stop-like manner. Its mixing-active structure comprises two mirror symmetric surface regions, between which a flow-through opening is located; the latter has a central narrows and two lens-like zones which extend transversely to the narrows. The surface regions can lie on two planes which are inclined with respect to one another and of which the crossing linexe2x80x94when projected perpendicularly onto a pipe cross-sectionxe2x80x94forms a centerline of the narrows. In a fluid which flows through the central narrows there arise vortices as a result of the stop action of the narrows which on the one hand have a mixing effect on admixed additives and on the other hand cause a relatively large pressure drop. As a result of the mirror symmetry a low material exchange takes place between the pipe halves which are given by the crossing line and the centerline.
Flange mixers have the advantage with respect to static mixers which are arranged in pipe sections that they have a small volume. In accordance with certain computational regulations they are not considered as pressure containers due to their small volume and therefore do not require an elaborate testing procedure for an approval. A disadvantage is that the flange mixer consists only of one mixing element and that it thus has a limited mixing action.
It is an object of the invention to create an alternative to the known flange mixer which has an improved mixing action with low pressure loss. In the admixing of an additive using the mixing element in accordance with the invention the additive can be fed in via a large number of input locations, so that the mixing action of the flange mixer which consists of only one mixing element can be sufficient.
The mixing element is provided for a flange transition in a pipeline and can be mounted between two flanges of the pipeline. It comprises a mixing-active structure which is formed by one or two vanes within a ring. Two mutually inclined planes can be defined, with the one vane being arranged on the one plane or with the two vanes being arranged on the two planes. The two planes intersect at a crossing axis. Closed sub-surfaces as well as open pieces of surface of the vanes form a surface pattern which is asymmetrically formed with respect to the crossing axis. Through the asymmetric shape a fluid which flows through the pipeline can be deflected in such a manner that partial flows are deflected from one pipe half through sub-surfaces of the one plane into the other pipe half and encounter there largely non-deflected partial flows, with this also holding vice versa with respect to the other plane if on the latter there is a second vane having structure elements.
In the following the invention will be explained with reference to the drawings.